Conventionally, when water resistance is required for a portion in which an electric wire group is passed through a hole that penetrates a wall, a sealing structure is provided around the hole. The sealing structure described in Patent Document 1 is known as such a sealing structure for a penetrated portion. In this sealing structure, a grommet through which the electric wire group (wire harness) is inserted is attached to the wall provided with a through hole, and a flexible lip having a large diameter that is provided in the grommet is brought into elastic contact with the periphery of the through hole to seal the through hole.